undo log
A logging mechanism in InnoDB used for transaction rollback and multi-version reads. It records the old values of data before modification, forming a version chain that supports MVCC snapshot reads.
Timeline (last 90 days)
InnoDB's write path is log-first: any modification is first written to the redo log, then dirty pages are flushed asynchronously; after a crash, recovery is done by replaying redo, and rollback and multi-version reads are achieved through undo.
Atomicity in the ACID properties of database transactions is implemented through Write-Ahead Logging (WAL) and undo log mechanisms.
All Facts (2)
InnoDB's write path is log-first: any modification is first written to the redo log, then dirty pages are flushed asynchronously; after a crash, recovery is done by replaying redo, and rollback and multi-version reads are achieved through undo.
50%UnverifiedAtomicity in the ACID properties of database transactions is implemented through Write-Ahead Logging (WAL) and undo log mechanisms.
50%